The invention discloses an engine cooling 
system and a cooling method. The cooling 
system comprises a water pump, a double-valve temperature 
regulator, a 
machine oil cooler, a 
water jacket of a cylinder body, a 
water jacket of a cylinder cover, a water tank radiator and an EGR cooler. The cooling 
system adopts a water passage circulation as follows: when the engine is started, the water pump begins to work; cooling liquid firstly flows into the 
machine oil cooler and enters in the 
water jacket of the cylinder cover to cool the key area of the cylinder cover, and then enters in the water jacket of the cylinder body from a 
gasket circulating hole of the cylinder cover to cool the cylinder body and the EGR cooler. The cooling liquid in the cooling system firstly cools the cylinder cover to reduce the temperature of the cylinder cover by 10 DEG C to 15 DEG C, enhance 
aeration efficiency, enlarge air inlet quantity, promote complete 
combustion, reduce the formation of 
discharge objects andenhance output efficiency; After cooling the cylinder cover, the cooling liquid enters in the cylinder body for cooling the cylinder body; the higher temperature of the cylinder body can reduce friction, improve 
fuel efficiency, enhance the output efficiency and reduce 
peak value pressure and temperature in the cylinder.